As Celtic prepare to kick off their pre-season with a friendly against Scott Brown’s Ayr United on Friday night, the club have sent a message to the supporters planning to travel and attend the game. Ayr expects a full house for the match after releasing extra tickets to Celtic after the fans sold out their initial allocation within hours of release. The Scottish Championship side is due to a healthy payday from the fixture as the Celtic fans look to see their team for the first time since clinching the Scottish Cup against Rangers last month. And as excitement builds around the fixture, Celti…